An inpatient program with selected overnight stays, for childhood and adolescent neuropsychiatric disorders has been initiated. The conditions currently under study are hyperactivity and Gilles de la Tourette syndrome. Pharmacological compounds under study in these disorders include methylphenidate, amphetamine, piribedil, clozapine, and haldol. Pharmacokinetic studies with behavioral correlations are on-going. Central neurotransmitters and nucleotides, and their metabolites are being studied in serum and urine. Early unpublished findings indicate that the amphetamine half-life in children is about 1/3 that of adults. Behavior and motor activity response do not correlate with serum amphetamine levels. These responses occur at or before the peak blood level is reached.